This specification is based on the European application No. 00 106 891.5 forming the priority application.
1. Field of the Invention
The present invention relates to an internal combustion engine having a housing member which is closed at opposite ends by cover plates; having a drive shaft extending through said housing member perpendicularly to the cover plates; further having a piston member located inside the housing member and eccentrically supported on a eccentric portion of the drive shaft and guided to orbit without rotation when the combustion engine is in operation; further having a plurality of radially and equidistantly arranged vanes sealed against the cover plates, the housing member and the piston member.
2. Description of the Related Art
Internal combustion engines which do not comprise pistons which perform rectilinear stroke movements and comprise rather pistons which perform rotary movements or orbital movements incorporate considerable advantages over engines with rectilineary moving pistons.
Such advantages are small overall measurements, low weight and a rapid response regarding power changes. The reason thereto is that the pistons of such combustion engines are designed as rotors which are directly mounted on the drive shaft and perform a uniform rotating or orbiting, resp. movement, not subject to accelerations and decelerations and which are not subjected to inertias, unlike the pistons of conventional internal combustion engines. Also, since the combustion chambers of such combustion engines are located generally at a center area of the engine and in case of engines having orbiting movements of their pistons, specifically in a point-symmetrical arrangement relative to the drive shaft, the dynamic characteristics of the overall engine is not affected by the moving pistons.
An important feature of internal combustion engines of which the rotor performs a continuous, uniform orbiting movement around the drive shaft lies in the fact that the engine includes a plurality of separate combustion chambers, each providing favorable conditions for the combustion.
The main structural elements of combustion engines with an orbiting piston are the engine housing (or case, resp.) in the shape roughly of a flat box, which is closed at its top and at its bottom by cover plates, a drive shaft extending perpendicularly to the cover plates, which drive shaft has an eccentric portion, corresponding to the crankshaft of conventional internal combustion engines. A rotor operating as the piston member is mounted in the engine housing onto the eccentric section of the drive shaft. A number of blades or vanes, resp. which are sealed against the top cover plate and bottom cover plate extend between the rotor and the engine housing and are connected in such a manner to the rotor and to the engine housing that they can perform pivoting movements when the engine is in operation. These blades or vanes, resp. are, thus, arranged roughly in a star-like arrangement around the rotor and define the various combustion chambers.
The side surface portions of the rotor facing the combustion chambers may have additional depressions and/or projections, ledges for providing an improved lending or mixing, resp. of the fuel and air during the intake stroke phase, and may additionally be shaped that a layer-by-layer combustion of the fuel/air mixture occurs upon the ignition such that a high economic operation of the engine is arrived at.
The sealing members which are located between the orbiting rotor and the top and bottom cover plates are ordinary sealing strips or sealing rings which are spring biassed against the corresponding surfaces.
A well known internal combustion engine having a rotating rotor is the design of Wankel. A drawback of this Wankel engines are the rather elongate, stretched combustion chambers causing a inferior combustion of the air-fuel mixture causing a high fuel consumption. Furthermore, the inner side walls of the housing have a trochoidal from. The rotor is provided with sealing strips which wipe over these inner trochoidal side walls. This leads to serious vibrations of the sealing strips and to a high wear due to the continuous changing of the contour of the surface of these inner side walls. Also, the trochoidal surfaces lead to an uneven heating thereof, such that the combustion chamber shifts relative to the housing so that thermal tensions are produced which, among others, distort the trochoidal surface of the inner side walls of the housing of the engine.
A number of publications disclose internal combustion engines in which the piston does not make a simple rotary movement, but rather an orbiting movement around the center axis of the drive shaft. Such engines are disclosed e.g. in the specification of the U.S. Pat. No. 3,703,344 to Ritter and the French Patent specifications FR 2,180,346 and FR 1,366,410.
In these and other known engines the orbital motion of the piston member is generally achieved in that three additional eccentrical units are mounted at both sides of the piston member which eccentrical units feature an eccentricity of the main eccentric portion of the drive shaft. Furthermore, additional eccentric units are located in recessed areas in the cover plates and side surfaces of the orbiting piston. These designs do, however, not allow the small rotating motions of the piston member relative to the drive shaft which occur during its orbiting movement. Moreover, these known designs necessitate relatively large overall dimensions of the engine, a relatively high weight of the piston member and specifically a highly complex lubricating system.
Also to be mentioned is the U.S. Pat. No. 3,787,150 of Sarich. The vanes or blades, resp. of the Sarich engine are guided at one end in the engine housing in such a manner, that they perform analogue to sliders a rectilinear movement when the piston member performs its orbiting motions. The opposite ends of the vanes are received in tangentially extending slots in the orbiting piston. However, this design necessitates quite complicated mounting and sealing structures especially at the piston, and specifically the mounting structures in the piston are subject to considerable wear.
An object of the present invention is to provide a internal combustion engine with a piston member supported to perform an orbiting movement in which the vanes are supported and guided in a manner which gives rise to a minimum of friction and wear, which allows small overall dimensions and a simple lubrication system.
A further object is to provide an internal combustion engine with a piston member supported to perform an orbiting movement which includes a plurality of first equidistant cylinder shaped pivot bodies, each received for rotation in a corresponding first recess formed in its housing member and having a slot extending in the direction of its generatrix, in which slot a first end section of a corresponding vane is received for a free reciprocating sliding movement therein; and including a plurality of second equidistant cylinder shaped pivot bodies, each received for rotation in a corresponding second recess formed in mentioned piston member and having a slot extending in the direction of its generatrix, in which slot a second end section of a corresponding vane is received for a free reciprocating sliding movement therein; whereby in operation of the internal combustion engine each vane is free to perform reciprocating and pivoting movements to induce the orbital motion of the piston member relative to the housing member.
Since the width of such an engine is determined by the eccentricity of the piston member supported on the eccentric portion of the drive shaft, specifically by the radius of the eccentric portion, thus the size of the bearing between the piston member and the eccentric portion, by the dimensions of the needed oil wiping structures which are mounted in the piston member and specifically by the overall mechanism, i.e. structures which in operation produce the orbital motion of the piston member, the engine in accordance with the present invention has the advantage, that the vanes which divide the space between the piston member and the housing member into individual combustion chambers are pivotally mounted by pivot bodies to the piston member and by further pivot bodies to the housing member, whereby the dimensions of the combustion engine are determined by the minimal possible distance between the pivot axes of mentioned pivot bodies, thus the overall dimensions of the engine can be kept small. Furthermore, since the vanes are received for a free reciprocating movement in the slots of the pivot bodies, the wear can be kept at a low value. A impacting of the vanes at the respective end positions of their reciprocating movements in the slots may thus be avoided by mechanically acting springs and/or a fluid damping arrangement.
The axial length of the first pivot bodies which are mounted in the housing member may, according to a further embodiment, exceed the overall thickness of the housing member and may be supported for rotation in the cover plates of the engine.
Likewise, the axial length of the second pivot bodies which are mounted in piston member may also exceed the overall thickness of the piston member and may be supported for rotation in rotating disks in the cover plates, in which case the piston members are eccentrically supported in these disks with an eccentricity which equals the eccentricity of the piston member.
A further advantage of the vanes being mounted in pivot bodies is that the acceleration of the center of gravity of the vanes can be equalized and that, furthermore, the transmission of the inertia of the vanes to the housing member during the compression stroke and to the rotor during the combustion stroke allows to use the inertia of the blades as the driving force. This allows a decrease of the overall dimensions of the combustion engine, to simplify its construction, to decrease the friction and, thus, simplify the lubrication system.